The present invention relates to a volatile, residue free peroxide antimicrobial composition, which can be applied as a penetrating and durable, fine aerosol, that has superior strength with respect to decontaminating buildings infected with bacteria, fungi, virus or fungal or bacterial spores.
The present invention is also directed to a process for decontaminating large man made structures and the air contained in these.
Disinfecting biologically contaminated large man-made structuresxe2x80x94as for example shopping malls, sports complexes, high rises, subway systems, factories, etc.xe2x80x94as well as the air contained in these structures is an extremely challenging undertaking and none of the presently available methods are satisfactory.
The most widely used method is fumigation with formaldehyde. Formaldehyde is a suspected carcinogenic and a potent allergen which, due to inevitable residues left after a treatment, severely limits its usefulness in structures inhabited by man.
Numerous attempts have been made to use oxidizing gases such as ozone or chlorine dioxide for decontaminating large buildings. However, the results have invariably been very disappointing. This is to some extent due to the inherent inability of gases to penetrate a porous structure within a reasonable time. In fine pores diffusion is the only way for a gas to spread, and this process is slow. Mainly, though, the failure of ozone and chlorine dioxide in building decontamination is due to the instability and extreme reactivity of these gases. They are very toxic to man and will also corrode virtually any oxidizeable material, (metals, wood, textiles, plants, plastics, etc.) Actually the major part of these gases will be consumed in unwanted oxidation reactions, that cause collateral damage, and for health and safety reasons is basically not possible to apply these gases at the levels required for efficient decontamination to take place.
From a health and environmental point of view disinfecting agents based on peroxides, such as hydrogen peroxide, peracetic acid and like, is much to be preferred. Their oxidizing strength, without being excessive, in principle is adequate for killing virtually all microbes. Unfortunately hydrogen peroxide or other peroxides are too unstable and hazardous to allow fumigating with their vapors.
High density, fine aerosols (aerosol droplet diameter less than 50 micron) of aqueous peracetic acid, hydrogen peroxide or combinations thereof, suitable for disinfecting are only sufficiently stable at 100% R.H., and the commercial fog-disinfecting methods using peroxides are only suitable for confined spaces where all materials and equipment are corrosion resistant or protected.
The objective of said invention is to provide an antimicrobial composition that can be applied at ambient conditions as a high density, durable fine aerosol having superior disinfecting strength with respect to microbes and spores thereof adhered to inanimate surfaces as well as with respect to airborne microbes and microbial spores, such an aerosol being imminently suitable for emergency decontamination of buildings and spaces infected with hazardous microbes or spores thereof.
As a result of extensive research, I have found that a mixture of hydrogen peroxide and tert-butyl hydroperoxide in propylene glycol or other water compatible glycols can be converted to a high density, durable fine aerosol, using conventional thermofogging equipment (see below), without appreciable loss of peroxide activity through thermal decomposition, and that such aerosols manifest unexpected high disinfecting strength with respect to microorganisms including fungal and bacterial spores without causing staining, corrosion or irritating odors. The use of a combination of hydrogen peroxide and tert-butyl hydroperoxide for bleaching of pulp has been described in U.S. Pat. No. 3,645,840. However, it is by no means obvious how the disclosures of U.S. Pat. No. 3,645,840 can be applied to an aerosol process for disinfecting buildings. U.S. Pat. No. 5,147,884 describes antimicrobial composition containing tert-butyl hydroperoxide and a monophenylglycol ether.
In the disinfecting method according to this invention the peroxide antimicrobial agent is converted into a fine aerosol using various types of xe2x80x9cthermofoggersxe2x80x9d, such as for example a pulsejet fogger or an electrical fogger with a flash heating system. Examples of pulsejet thermofoggers are xe2x80x9cPatriotxe2x80x9d and xe2x80x9cBlack Hawkxe2x80x9d manufactured by Curtis Dynafog Corporation, Ltd., Indianapolis, and an example of a suitable electrical thermofogger is xe2x80x9cFogmaxxe2x80x9d manufactured by CITC, Lynnwood, Wash. Normally the high temperature in thermofoggers will destroy any peroxide. However, as mentioned above, I have discovered combinations of peroxides and carriers that can resist the high temperatures encountered in thermofoggers, making this ideal aerosol technique available to generate fine, high density, durable aerosols of peroxides. The fine aerosol produced in this manner will spread much like a gas, which makes it ideal for decontamination of large structures as well as inaccessible areas of buildings. However, in contrast to a gaseous agent, once an aerosol according to this invention has settled on a surface, it behaves like a liquid, that is, the agent can be transported by capillary action deep into a porous material, which is impossible with ozone or chlorine dioxide. The peroxide disinfecting method according to this invention kills mold, bacteria and fungi as well as spores thereof. The same oxidation reaction also degrades it and neutralizes the odor compounds from mold, fungi and bacteria (MVOC).
Another advantage of the disinfecting method according to this invention is that airborne microbes are disinfected with the same efficiency as those adhered to surfaces. Furthermore airborne particulate matter is removed from treated air spaces through agglomeration with the aerosol droplets, leaving the treated air virtually free from microbes and their spores.
The present invention provides a safe and effective method of sanitizing surfaces and ambient air by removing, reducing or retarding the growth of pathogenic microorganisms and molds without the use of substances that are toxic to humans and without leaving any permanent residue.
As the peroxide used as component (A) of said invention, commercially available hydrogen peroxide aqueous solutions can be used favorably.
Next, the volatile, organic peroxide used as component (B), is commercially available t-butyl hydroperoxide.
The content of the hydrogen peroxide used as component (A) in the biocidal composition is generally 0.5-60 wt %, preferably 0.5-30 wt %, and more preferably 0.5-20 wt %. For practicality, 3-20 wt % is most favorable. The content of t-butyl hydroperoxide, which is component (B), is 0.5-60 wt %, preferably 0.5-30 wt %, and more preferably 0.5-10 wt %. For practicality, 3-10 wt % is most favorable.
If component (A) or (B) is lower than said range, the disinfecting action is low, when component (A) or (B) is greater than said range, the product becomes difficult to handle as a biocidal composition.
The solvent carrier (C) of the biocidal composition in said invention is important for thermal stability, for aerosol forming properties as well as for obtaining high disinfecting strength. After extensive research I have found that mixtures of water and a low volatile, water compatible glycol or glycol ether are preferable, and most preferable are mixtures of propylene glycol and water where the content of propylene glycol in water is 10-90 wt %.
The biocidal composition of the present invention is normally manufactured by dissolving hydrogen peroxide (A) and t-butyl hydroperoxide (B) in a mixture of water and propylene glycol (C). The content of propylene glycol (C) used in the biocidal composition in said invention is selected from a range of 5-99 wt %, preferably 50-95 wt %, and more preferably 60-90 wt %.
In the biocidal composition of the present invention, it is preferable to add a surfactant. As the surfactant, cationic surfactants such as aryl-alkyl or dialkyl dimethyl ammonium halides, nonionic surfactant such as polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, amine oxides, etc., and anionic surfactants such as soaps, alkyl sulfates, and alkylbenzenesulfonates, etc., can be utilized. It is preferable for the quantity of the surfactant added to be 0.1-10 wt % in the biocidal composition. By the addition of a surfactant, it is possible to assist in the penetration of the biocidal composition with respect to the bacterial bio-film, mold or spore coating and to enhance the biocidal effect.
The biocidal composition of the present invention is applied as a fine aerosol using thermofogging equipment described above, and it is possible to disinfect spores, bacterial bio-films or molds effectively by contacting with said fine aerosol.
By thermal fogging, the biocidal composition of this invention is dispersed in 10-20 micron particle sizes and the treated building is kept closed for a minimum of twenty-four (24) hours for treatment to occur.
No rinsing of treated surfaces is required after or prior to application of the disinfecting aerosol according to this invention.
Typical bacteria which can be disinfected with the composition of this invention include: staphylococcus aureus, staphylococcus pyogenes, streptococcus hemolyticus, streptococcus dysgalactiae, mycobacterium tuberculosis, salmonella typhosa, salmonella typhimurium, salmonella pullorum, hemophilus parasuis, clostridium perfringens, mycoplasma synoviae, mycoplasma hyopneumoniae, pasteurella multocida, klebsiella pneumoniae, staphylococcus epidermis, streptococcus agalactiae, streptococcus fecalis, listeria monocytogenis, mycobacterium tuberculosis, salmonella choleraesuis, salmonella enteritidis, pseudomonas aeruginosa, clostridium tetani, diplococcus pneumoniae, mycoplasma gallisepticum, escherichia coli, pasteurella hemolytica, alcaligenes faecalis, salmonella gallinarum, salmonella arizonae, salmonella schotimuelleri, staphylococcus hyicus, streptococcus pyogenes, haemophilus parasuis; and, bordetella bronchiseptica. 
Fungus types, which may be disinfected by the composition of this invention, include: aspergillus fumigatus, aspergillus glacus, aspergillus nidulans, aspergillus flavus, aspergillus niger, fusarium solani; and penicillium variable.
Spore types, which may be disinfected by the composition of this invention, include: Bacillus anthracis, B., and (bacterial spores) and Stachybotrys, Aspergillus, Penicillium, Trichoderma and Alternaria spp. (fungal spores).
Viruses which are disinfected by this composition include: Adenoviridae (Egg Drop Syndrome), Herpetoviridae (Infectious Bovine), Rhinotracheitis (Aujeszky""s Disease), Feline Herpes, Iridoviridae (African Swine Fever), Parvoviridae, (Canine Parvovirus), Poxviridae Pseudo (Cowpox), Coronaviridae (Transmissible Gastro-Enteritis), Avian Infectious Bronchitis, Canine Coronavirus, Orthomyxoviridae (Avian Influenza), Paramyxoviridae (Newcastle Disease), Distemper, Picornaviridae (Swine Vesicular Disease), Foot and Mouth Disease, Reoviridae Gumboro (IBD), Retroviridae (Maedi and Visna), AIDS.